Over the next 90 days, the probe is due to dig into the permafrost to look for evidence of the building blocks of life.

Cheers swept through Mission Control at NASA’s Jet Propulsion Laboratory when the touchdown signal from the Phoenix Mars Lander was detected after a nail-biting descent. "Phoenix has landed! Phoenix has landed! Welcome to the northern plains of Mars," deputy systems engineer Richard Kornfeld announced.

The first data from the probe indicated that it was sitting almost exactly level on its landing site in Mars' Vastitas Borealis region.

“In my dreams it couldn’t have gone as perfectly as it went,” NASA project manager Barry Goldstein said. “It went right down the middle.”

Among Phoenix’s first tasks were to check its power supply and the health of its science instruments, and unfurl its solar panels after the dust settled. Then the first pictures were taken and transmitted to Earth. The pictures showed the fully deployed solar panels, the soil under one of Phoenix's landing pads and long-range looks toward the horizon of the northern plains.

The plains appeared to broken up by polygon-shaped fractures — as expected, based on orbital imagery. Scientists say such patterns arise in the polar regions of Earth as well as Mars, due to wind action or repeated cycles of freezing and thawing.

"Underneath this surface, I guarantee, is ice," said Peter Smith, the Phoenix mission's principal investigator from the University of Arizona at Tucson.

Dan McCleese, a chief scientist at JPL, said the polygonal terrain was "absolutely beautiful."

"It looks like a good place to start digging," he said.

Seven minutes of terror
Phoenix plunged into the Martian atmosphere at more than 12,000 mph (19,200 kilometers per hour) after a 10-month, 422 million-mile (675 million-kilometer) voyage through space. It performed a choreographed dance that included unfurling its parachute, shedding its heat shield and backshell, and firing thrusters to slow to a 5 mph (8 kph) touchdown.

The automated descent was dubbed "the seven minutes of terror" for good reason. More than half of all nations’ attempts to land on Mars have ended in failures.

Smith said the room was thick with tension during those seven minutes. "I couldn't let go of the chair," he said. "I had a grip on it."

Sunday's touchdown was the first successful soft landing on Mars since the twin Viking landers touched down in 1976. NASA’s twin rovers, which successfully landed on Mars four years ago, used a combination of parachutes and cushioned air bags to bounce to the surface.

Phoenix’s landing was a relief for NASA, since Mars has a reputation for swallowing spacecraft. More than half of all nations’ attempts to land on Mars have failed.

NASA Administrator Mike Griffin marveled at the precision of the Phoenix team members' aim, saying they achieved better than "one part in 10 million of accuracy." Ed Weiler, NASA's associate administrator for the science missions directorate, said that was the equivalent of hitting a golf ball in Washington — to make a hole-in-one on a golf course in Australia.

"And you have to remember, that hole is moving," JPL Director Charles Elachi quipped.

Taking in the arctic sights
Phoenix’s target landing site was a 30-mile-wide (50-kilometer-wide) shallow valley in the high northern latitudes, similar in location to Earth’s Greenland or northern Alaska. The site was chosen because images from space spied evidence of a reservoir of frozen water close to the surface.

Like a tourist in a foreign country, the lander initially will take in the sights during its first week on the Red Planet. It will talk with ground controllers through two Mars orbiters, which will relay data and images.

Phoenix is equipped with an 8-foot-long (2.4-meter-long) arm capable of digging trenches in the soil to get to ice that is believed to be buried inches to a foot deep. Then it will analyze the dirt and ice samples for traces of organic compounds, the chemical building blocks of life.

The lander also will study whether the ice ever melted at some point in Mars’ history when the planet had an environment warmer than the current harsh, cold one it currently has.

Scientists do not expect to find water in its liquid form at the Phoenix landing site because it’s too frigid. But they say that if raw ingredients of life exist anywhere on the planet, they likely would be preserved in the ice.

Phoenix, however, cannot detect signs of alien life that may exist now or once existed.

The only other time NASA searched for chemical signs of life was during the Viking missions. Neither lander found conclusive evidence of life.

Avoided Polar Lander's doom
Phoenix avoided the doom of its sister spacecraft, the Mars Polar Lander, which in 1999 crashed into the south pole after prematurely cutting off its engines. The Polar Lander loss, along with the earlier loss of an orbiter the same year, forced NASA to overhaul its Mars exploration program.

Phoenix, named after the mythical bird that is reborn from its ashes, inherited hardware from a lander mission that was scrapped after the back-to-back Mars losses, and carries similar instruments that flew on Polar Lander.

Built by Lockheed Martin Corp., Phoenix is the first mission from NASA’s Scout program, a lower-cost complement to the space agency’s pricier Mars missions. It cost $420 million to develop and launch Phoenix, compared with the $820 million originally invested in the twin rovers.

The rovers have dazzled scientists with their Energizer Bunny-like ability to keep going and their geologic findings that ancient Mars once had water that flowed at or near the surface.

Mission managers do not expect Phoenix to be as hardy as the rovers, since winter will set in later this year at the landing site with fewer hours of sunlight available each day to power the lander’s solar panels.

This report includes information from The Associated Press and msnbc.com.